Have you tried putting a piece of worn clothing in with her. Sometimes its the smell of you she misses. My DD hated the dummy and i tried everything to get her to take one as she was using my breast as a soother. MAybe try using your finger until she is laying down then slowly removeing it.

Are you using music?? I found the mobile would excite DD but music from a lullaby CD really soothed her. I also elevated the mattress a little cos when i held her she was more upright.

Once DD learned to self settle she was great. Does she feed to sleep or do you rock her or something??? Motion can be good cos they dont realise your moving round when your putting them down but the sudden stoping can also wake them up. i liked patting or rubbing to sleep this way you can slowly stop and they are already laying down.